The disclosure relates generally to additive manufacturing, and more particularly, to a damaged applicator identifier system for an additive manufacturing (AM) system and an AM system including the damaged applicator identifier system.
Additive manufacturing (AM) includes a wide variety of processes of producing an object through the successive layering of material rather than the removal of material. As such, additive manufacturing can create complex geometries without the use of any sort of tools, molds or fixtures, and with little or no waste material. Instead of machining components from solid billets of material, much of which is cut away and discarded, the only material used in additive manufacturing is what is required to shape the object.
Additive manufacturing techniques typically include taking a three-dimensional computer aided design (CAD) file of the object to be formed, electronically slicing the object into layers, e.g., 18-102 micrometers thick, and creating a file with a two-dimensional image of each layer, including vectors, images or coordinates. The file may then be loaded into a preparation software system that interprets the file such that the object can be built by different types of additive manufacturing systems. In 3D printing, rapid prototyping (RP), and direct digital manufacturing (DDM) forms of additive manufacturing, material layers are selectively dispensed, sintered, formed, deposited, etc., to create the object.
In metal powder additive manufacturing techniques, such as direct metal laser melting (DMLM) (also referred to as selective laser melting (SLM)), metal powder layers are sequentially melted together to form the object. More specifically, fine metal powder (raw material) layers are sequentially melted after being uniformly distributed using an applicator on a metal powder bed or build platform. The metal powder build platform can be moved in a vertical axis. The process takes place in a processing chamber having a precisely controlled atmosphere of inert gas, e.g., argon or nitrogen. Once each layer is created, each two dimensional slice of the object geometry can be fused by selectively melting the metal powder. The melting may be performed by a melting beam source such as an electron beam or a high powered laser (in latter case, e.g., a 100 Watt ytterbium laser), to fully weld (melt) the metal powder to form a solid metal. The melting beam moves in the X-Y direction using, e.g., scanning mirrors, and has an intensity sufficient to fully weld (melt) the metal powder to form a solid metal. The metal powder build platform is lowered for each subsequent two dimensional layer, and the process repeats until the object is completely formed. In order to create certain larger objects faster, some metal additive manufacturing systems employ two or more high powered melting beam sources that work together to form an object.
In metal powder AM systems, an applicator, sometimes referred to as a recoater or wiper, is used to apply each thin layer of raw material, e.g., metal powder, over the build platform and any previously formed layers of the object. Each applicator includes an applicator element in the form of a lip, brush, blade or roller made of metal, plastic, ceramic, carbon fibers or rubber that spreads the metal powder evenly over the build platform. An active or primary applicator is used to start the build. Because the applicator element is oftentimes made from a softer material than the actual manufacturing material, it is susceptible to damage during use. A damaged applicator may have a defect in the form of a misalignment with the build platform or some sort of defective shape in its applicator element that is transferred into the next layer of raw material applied to the build platform. In any event, the melting beam source subsequently prints the defect into the object. For example, a defective shape in the applicator element can take a variety of forms such as a ridge, ripple, bump, etc., in the layer of raw material. If a defective shape occurs during use, the defective shape will be continuously wiped into the metal powder and the melting beam source will solidify this area as a repeating defect in the object. In order to address this challenge, some current systems change the applicator element between AM system uses, which may require an unscheduled work stoppage and may prolong the use of a damaged applicator until an effective stopping point is reached in the process. Alternatively, some current systems employ either replacement applicators or replaceable applicator elements to replace a damaged applicator when damage is identified on the applicator element, e.g., during use of the AM system. Current systems that identify damage to the applicator element do so by direct analysis of the applicator element or by indirect analysis of drag forces on the applicator experienced by the transport system that moves the applicator.